1. Technical Field
The present invention generally is in the field of the chemical treatment of pulp and paper mill sludge to recover chemical values. The present invention more specifically is in the field of the bioconversion of pulp and paper mill sludge into value added products. The present invention also more specifically is in the field of the production of cellulase enzymes from delignified lignocellulosic materials found in pulp and paper mill waste streams. The present invention further more specifically is in the field of ethanol production from pulp and paper mill waste streams.
2. Prior Art
Pulp and paper mill sludge is a solid waste material generated from pulping and paper-making operations. Because of high glucan content and its well-dispersed structure, pulp and paper mill sludge is well suited for bioconversion into value-added products. Pulp and paper mill sludge also has high ash content originated from inorganic additives used in pulp and paper making processes, which causes hindrance to bioconversion.
Cellulase enzyme is one of the major cost factors in production of cellulosic ethanol. For this reason, much of the recent research efforts on cellulosic ethanol have been devoted to cellulase enzymes, such as on cellulase producing microorganisms targeting efficient production of cellulase enzymes and improving the characteristics of the enzymes on the molecular level. Also related to cellulase enzyme is pretreatment research, the goal of which is to reduce the enzyme loading. These are important and meaningful tasks in the research of cellulosic ethanol. There is yet another important issue pertaining to cellulase production, namely, the feedstock. From the dearth of currently available literature information, very little attention is being paid to this issue at the moment. Cellulases are currently produced commercially, but in relatively small scale because of its limited market. With the current market value of cellulase, the cost of feedstock is of minor concern. However, this will no longer be the case in the world of cellulosic ethanol, where low cost feedstock is required for production of cellulase. In an economic sense, it is as important as enzyme improvement or devising an efficient pretreatment.
Accordingly, there is a need for improved methods for the chemical treatment of pulp and paper mill sludge to recover chemical values. There also is a need for methods for the bioconversion of pulp and paper mill sludge into value added products. There additionally is a need for methods for the production of cellulose enzymes from delignified lignocellulosic materials found in pulp and paper mill waste streams. There further is a need for methods for ethanol production from pulp and paper mill waste streams. It is to these needs, among others, that this invention is directed.